<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    function mother() {
      var i = 0;
      return function() {
        i++;
        console.log(i);
      }
    }
    var get1 = mother();
    get1(); // 1
    var get2 = mother();
    get2(); // 1
    get1(); // 2
    get2(); // 2
  </script>
</body>
</html>